This application claims priority to International Application No. PCT/GB99/04259 which was published on Jun. 29, 2000.
This invention relates to an autonomous aplliance, and more particularly to a robotic floor cleaning device, typically a robotic vacuum cleaner.
There has long been a desire for a vacuum cleaner which is capable of cleaning a room without the need for a human user to push or drag the cleaner around the room. A number of robotic or autonomous vacuum cleaners have been proposed. The control mechanism for these cleaners includes sensors for detecting obstacles and walls so that the vacuum cleaner is capable of guiding itself around a room so as to clean the carpet or other floor covering without human intervention. While autonomous cleaners are generally capable of dealing with most rooms, there are certain limits on what such cleaners are capable of and autonomous cleaners have been known to struggle in avoiding certain types of obstacle in a room. One particularly problematic type of obstacle is the threshold to a descending stairway. Some autonomous cleaners have been sold with instructions not to use them in rooms having certain types of feature. Clearly, this limits the usefulness of an autonomous cleaner.
Some known autonomous floor cleaning devices use navigation beacons or transponders placed around a room. Signals received at the cleaning device from the beacons help the cleaning device determine its position in the room Typically, the cleaning device determines its position within the room by a triangulation method which uses a signal received from each of the beacons, The location of the beacons in the room may be known by the cleaning device in advance or the cleaning device may establish their location during a trip around the perimeter of the room. Such beacons are of a high enough power to allow a cleaning device to receive a signal from each of the beacons, wherever it may be positioned In the room, A cleaner of this is shown in U.S. Pat. No. 5,682,313 (Edlund el al.). The cleaner firstly performs a wall tracking routine using its ultrasonic sensors and registers the position of the transponders around the room during this routine. The cleaner is subsequently able to determine its position within the room by using a signal received from each of the transponders and the knowledge of the location of the transponders within the room that it has gained during the wall tracking routine. The use of an infrared beacon as a navigational aid is shown in U.S. Pat. No. 5,165,064.
EP 0 774 702 describes a boundary detection system for an automated robot in which the inner and outer boundaries of a working area are defined by magnetic markers.
The present invention seeks to allow an autonomous vehicular appliance to be used in a wider range of environments.
A first aspect of the present invention provides an autonomous vehicular appliance in combination with at least two threshold locators which can be placed, in use, at locations to define at least part of a boundary of an area within which the autonomous vehicular appliance is to be confined at least temporarily, the threshold locators differing in the signal that they transmit, the appliance being provided with a navigation system for navigating the appliance around the area and a detection system to allow the appliance to detect the presence of the threshold locators, the detection system comprising means for receiving a signal from a threshold locator and wherein the appliance is arranged to use the received signal to detect the part of the boundary defined by the threshold locator and, upon detecting the first threshold locator, to prevent itself from crossing the part of the boundary marked by the threshold locator and, upon detecting the second threshold locator, to prevent itself from crossing the part of the boundary marked by the threshold locator until a certain condition has been met.
Other aspects of the present invention provide an autonomous vehicular appliance and a method of cleaning an area using an autonomous vehicular appliance.
The vehicle""s own navigation system comprises sensors that allow the vehicle to find features of the room, such as walls and obstacles, and to navigate around the room with respect to these. However, the vehicle may have difficulty in detecting certain features of the room and in recognising that these features form part of the boundary of the room within which the vehicle should remain. The threshold locators serve to define a boundary at these places and allow the vehicle to recognise that these places should form part of the boundary. This arrangement is particularly advantageous when the appliance is a robotic floor cleaning device and the threshold locators are used to define part of a boundary of a room which the floor cleaning device should not cross. The portable threshold locator is typically placed in doorways to confine the cleaning device to a room or at the top of a staircase to prevent the cleaning device falling down the stairs. Without the threshold locator, a doorway will usually be regarded by the cleaning device as an open space into which it can move. As well as use in defining the perimeter of the room, it can also be used to mark a boundary around obstacles within the room which the appliance may otherwise have difficulty in detecting, such as a plant with trailing leaves.
The threshold between areas (rooms) can be marked by using the threshold locator which transmits a different signal to the other threshold locators. The appliance treats the threshold between areas as one that should not be crossed until a certain condition is met. This condition can be when the appliance has completely traversed the area.
Use of the threshold locator allows the appliance to be used in rooms having a much wider range of features or obstacles. Thus, the appliance can be used in more rooms of a user""s home and requires less human supervision.